Battery not charging, lights not working, 120 works fine

[Biker16]

New to the Airstream life after my wife and I purchased a 71 Overlander this week. It is mostly original and in great shape for its age. Ended up with some problems today as we were in it cleaning and assessing what we need to do to get it going:

While on shore power with 120v working, the 12v system (lights, fans, etc) stopped working. Now my battery tender doesn’t even recognize the battery (pry due to the charge being too low).

Any ideas on the cause and fix would be appreciated!

[DKB_SATX]

Odds are that your converter-charger is dead or disconnected. For a while everything was working off the battery, which may be fully dead now.

Short-term, if you have a bigger/dumber battery charger it might get you back in business while you have 120v power available. Find your converter and check some things (this assumes you have a multimeter and know how to use one, but there are shade-tree ways to work around that esp for the 12v side, but I've personally never been a fan of spark-testing stuff):

1) Is it getting 120v AC power into it? (this could be as simple as it being unplugged, a bad breaker, etc.)
2) Is it an antique? If it's the original one, even if it works it's a primitive thing that should be upgraded.
3) If it's getting 120v input, is it putting out 13+ volts DC? (measure this as close to the converter as you can.) Does it have any fuses on the case? Check these.
4) If the converter is putting out useful DC voltage, trace the wires to the fuse block and then on to the battery and check the condition of any fuses and connections in that line.

[Biker16]

Thanks for the reply. I didn’t even think the whole converter could be disconnected because the fuses looked good. I ordered a new converter and I’m going to grab another battery. I’ll let you know what I come up with.

[Bill M.]

Your old converter needed changing whether it works or not. So you are going in the right direction. On some Airstream trailers there is a "mystery switch" that turns off the power to the converter. If you have one of these switches it is probably around the sofa area. I think the idea was you could turn it off for sleeping. My wife keeps a lot of stuff behind the sofa. I finally had to just tape the switch to keep the converter from getting shut off accidentally.

[Biker16]

Thanks for the feedback. I just got in a https://www.amazon.com/Progressive-Dynamics-PD9260CV-Inteli-Power-Converter/dp/B000GASX9O and plan to install it this weekend.

The front gaucho is out and I didn’t find any mystery switch so I don’t think that was the issue.

Is the converter I got put me on the right track? Is there anything else I need to charge the battery and run my 12v system?

[Biker16]

I got my PD9260C plugged into 120v. I have leads going to positive and negative terminals off the converter. I wanted to test the 12v fans/lights to ensure it was working and I’m not getting anything.

Any thoughts on the system I have purchased or where I went wrong along the way would help out.

[uncle_bob]

Hi

Your trailer is about 50 years old. It's a good guess that multiple folks have owned it. Various mods have been popular at various times and with different people. Your electrical system may not have any resemblance to what came from the factory. This is very much a "root around and see what's what" sort of adventure.

A "normal trailer" has a 12V DC bus bar and a bunch of thermal reset breakers coming off of it. Is / was yours ever normal? Who knows. The 12V bus is somewhere up in the front of the trailer. The batteries tie into it. To get to the rest of the system, it has to tie into it as well.

First step is to grab your multimeter, find the DC bus and see what voltage is on it. If the converter is off and nothing much is turned on, that voltage should match what you see on the battery posts. Now check the output of the converter. It should also measure the same voltage.

Next step: power up the converter. All the voltages you just measured should go up. The converter output will go up the most, the battery will go up the least (it's on a long wire and there is current flowing).

Assuming this all works out, your converter is indeed charging the battery. If it doesn't work out then there is a switch / fuse / wire / breaker / latching relay / whatever between the two that isn't doing the right thing. Trace the wire out and see what you run into. There are maybe 20 possible things that *could* be getting in the way. Easier to trace out what you have than to guess ...

Once you have that part running, there is a fuse panel ( or was ...) that feeds the lights and switches. It gets it's power from the DC bus. Your multimeter should measure the same voltage on it as on the bus. Again, if it doesn't .... something isn't doing the right job.

Probably best to take notes as you go along. They will be useful two years from now when a light stops working .....

Bob

[Al and Missy]

Originally Posted by Biker16

I got my PD9260C plugged into 120v. I have leads going to positive and negative terminals off the converter. I wanted to test the 12v fans/lights to ensure it was working and I’m not getting anything.

Any thoughts on the system I have purchased or where I went wrong along the way would help out.

It appears you have the positive of the converter connected to the big screw on the right side of your distribution panel and the negative to the big screw on the left. What I don't see is any return/ground wires connected to the multiple screws on the buss bars on the left. The power is going out from the converter but has no way to get back. Several possibilities:


1. Return side of all 12V loads are connected to the trailer frame/skin. In which case you need a heavy ground wire from the converter negative to the skin.

2. Return side of the loads goes to a common buss bar somewhere. You need to run a heavy wire from the converter negative to there or move them to the ground bussbars on your distribution panel.

3. You have the return wires hanging loose somewhere. You need to connect them to the ground bussbars on the distribution panel.

4. A combination of the above.


And the batteries need to be connected to the converter through appropriate fuses/circuit breakers.

[uncle_bob]

Hi

If we're getting into re-wiring, all of the wire gauges need to be appropriate to the task.

Bob